A primary use for the invention lies in resurfacing and repairing roadways and parking lots with hot asphaltic materials. The effects of the weather and traffic are to cause deterioriation and to create surface irregularities in paved surfaces. Hot asphalt repairs are made by spreading a quantity of hot asphalt or other particulate material on the damaged surface, followed by raking the repair material to fill holes and depressions while creating a smooth and level upper surface. It is usual to compact the repair material in place to seal it to the repaired surface and to provide a new surface which is smooth and resistant to weather damage. Most repair work of that kind is accomplished on roadways by employees or contractors of local governments.
Small holes are filled by hand, raked level, and the filling compacted with a heavy roller. It is hard work. It is messy and dirty, but it is effective if the repair material, when asphaltic, is used while hot and within a two-hour period beginning at the time the asphalt was produced. The two-hour time limit is a practical limiting factor for hot asphalt repairs. As the area of a road repair project is increased, logistical problems increase. These complexities increase costs and severely limit the area that can be repaired by the average patch repair crew.
Paving machines are available and they do an excellent job. They are costly, however, and must be moved from place to place with a trailer. Most of the available machines require a crew of six to nine workers. Fixed operating costs are so high that it is customary to employ two-way radio communication as a part of providing a continuous fresh supply of asphalt. Such machines are practical and necessary for the expeditious and economical accomplishment of long, continuous resurfacing tasks. They are entirely impractical for resurfacing short strips and patches which are spaced some on one street and others a few blocks away. It simply is too costly to employ six or nine people from one craft union and several from a trucking union to load and unload a machine costing tens or hundreds of thousands of dollars to effect medium sized repair jobs at a number of different locations.
The result, which can be verified in city after city from the largest metropolis to small villages, is that local governments make hand repairs until the repair jobs are too numerous or involve an area too large for the available manpower. Thereafter, no repair is made until the roadway has deterioriated to the point where the whold road, or much of it, requires resurfacing. At that point, a contract is let which will support use of a resurfacing machine and its related supporting industries.
That has been the procedure for years. Asphalt has been inexpensive. It has posed no special burden to resurface entire streets when their condition had deteriorated. But, asphalt uses large quantities of petroleum and costs have made it increasingly difficult to continue past practices.